1884.] G. Thibaut —-Vardlia Mlhira s Tanchasiddhantilcd. 
281 
find out why the Romaka uses instead of the simple Metonic period 
its 150th multiple. At first we have to ascertain the length of the 
solar year of the Romaka, by dividing the 1,040,953 civil days com - 
prised in the entire yuga by 2,850, the number of years ; when we 
obtain 365*^ 5^^ 55' 12"; a result showing, as of course we might 
already have inferred from the mere use of the Metonic period, that the 
Romaka uses not the sidereal solar year the uniform employment of 
which is so marked a feature of later Indian astronomy but the tropical 
solar year. Ror again is there any room for doubt concerning the origin 
of this determination of the solar year. It is the tropical year of 
Hipparchus or if Ave like of Ptolemy who adopted his great predecessor’s 
estimation of the time occupied by one tropical revolution of the sun 
Tvithout attempting to correct it although it is considerably too long. 
(^Cf. Ptolemy’s Syntaxis, Book III.) 
It is certainly a matter of interest to meet in one of the oldest 
Siddhantas with an estimation of the year’s length whose Greek origin 
it is impossible to deny. The comparison of the length of the year as 
fixed by the different Siddhantas on one side and the Greek astronomers 
on the other side is generally beset by considerable difficulties chiefly 
in consequence of the Hindu astronomers giving no direct information 
about the length of the tropical year, while the Greeks on their part 
speak in clear terms of the tropical year only, and oblige us to infer 
their opinions regarding the length of the sidereal year. It is of course 
easy enough to deduce the length of the one species of year from the 
length of the other if we are acquainted with the assumed yearly rate of 
the precession of the equinoxes. But it so happens that the determina¬ 
tion of the latter point is in many cases by no means easy. To take for 
instance the (published) Siirya Siddhanta we easily derive from its data 
the length of its sidereal year, viz., 365*^ 6^^ 12"^ 36'6® and, if we avail 
ourselves of the amount of yearly precession as stated in its tripras- 
nadhyaya, viz., 54", we find for the length of the tropical year 365*^ 5“^ 
50“^ 41'7®, which is a determination much more correct then that of the 
Greek astronomers. But I quite share the suspicion expressed by 
Professor Whitney (translation of the Siirya Siddhanta, p. 246 ff.) that 
the passage of the triprasnadhikara alluded to formed no part of the 
original Siirya Siddhanta, but is a later interpolation. It remains there¬ 
fore uncertain by what process the length of the sidereal year of the 
Siirya Siddhanta was determined ; the possibility of its being founded 
on the tro|3ical year of Hipioarchus and the Romaka Siddhanta is mean¬ 
while not to be considered as altogether excluded.* 
* The proposal made by Biot (Etudes sur T astronomie Indienne, p. 29) to 
account for the sidereal year of the Siirya Siddhanta by considering it as the 
